The hackers in the earlier attack claimed to access the passenger information by exploiting a rudimentary security flaw in MyBart.org, which is owned by BART. BART officials have declined to say whether the site was ever reviewed by outside security auditors.

The attacks follow a controversial move to disable cellular service in at least four San Francisco BART stations last week. BART management took that action to disrupt a planned demonstration that protesters were organizing online. BART officials said its decision to turn off the nodes that connected carriers to underground antennas was legal and necessary to prevent unsafe conditions in confined spaces. Critics have compared the move to those taken by former Egyptian President Hosni Mubarak to quash protests against his rule.

The BART demonstrations were protesting the fatal shooting by BART police in July of a homeless man who allegedly brandished a knife as he lunged at officers. ®